高斯消元模板题

把第i列除了第i行外所有的系数变成0

#include <bits/stdc++.h>
#define inf 2333333333333333
#define N 110
#define p(a) putchar(a)
#define For(i,a,b) for(int i=a;i<=b;++i)
//by war
//2020.9.10
using namespace std;
int n;
double t,eps=1e-7;
double a[N][N];
void in(int &x){
    int y=1;char c=getchar();x=0;
    while(c<'0'||c>'9'){if(c=='-')y=-1;c=getchar();}
    while(c<='9'&&c>='0'){ x=(x<<1)+(x<<3)+c-'0';c=getchar();}
    x*=y;
}
void o(int x){
    if(x<0){p('-');x=-x;}
    if(x>9)o(x/10);
    p(x%10+'0');
}

void gs(){
    For(i,1,n){
        t=a[i][i];
        For(j,i+1,n) t=fmax(t,a[j][i]);
        if(fabs(t)<eps){
            puts("No Solution");
            return ;
        }
        For(j,1,n){
            if(i!=j){
                double temp=a[j][i]/a[i][i];
                For(k,i,n+1){
                    a[j][k]-=a[i][k]*temp;
                }
            }
        }
    }
    For(i,1,n) a[i][n+1]/=a[i][i];
    For(i,1,n) printf("%.2lf\n",a[i][n+1]);
}

signed main(){
    in(n);
    For(i,1,n)
        For(j,1,n+1)
            scanf("%lf",&a[i][j]);
    gs();
    return 0;
}